The present invention relates to a hydraulic control device of a forklift truck.
A forklift truck generally uses a hydraulic cylinder as a mechanism for operating movable loading members of the forklift truck such as forks. For example, Japanese Unexamined Patent Application Publication No. H02-231398 discloses a hydraulic control device having a single hydraulic pump and a single electric motor that drives the hydraulic pump. The hydraulic pump is driven to rotate so as to operate hydraulic cylinders (lift cylinders) that lift and lower the forks and hydraulic cylinders (tilt cylinders) that tit the mast assembly of the forklift truck.
When a hydraulic control device which has a single hydraulic pump operates any selected one of a plurality of movable loading members, the hydraulic control device controls the operation of the hydraulic pump in accordance with a speed that is instructed for operating the selected loading member. However, when the hydraulic control device operates a plurality of movable loading members simultaneously, the hydraulic control device controls the operation of the hydraulic pump in accordance with a speed that is instructed for any specific one of the loading members, and it is difficult to operate the plural loading members at their respective instructed speeds.
The present invention, which has been made in view of the problem above, is directed to providing a hydraulic control device of a forklift truck that is capable of operating a plurality of loading members in a desired manner.